Development of nanoemulsion-based antimicrobial activity of cinnamon prepared with soy protein isolate-lecithin

The objective of the present research was to develop cinnamon oil nanoemulsions using soy protein isolate and lecithin as food grade natural emulsifiers. For this purpose, stable cinnamon oil nanoemulsion (droplet diameter of 141.2 nm) prepared by ultrasonic emulsification. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of free and nanoemulsified cinnamon oil against Escherichia coli, Enterococcus faecium, Bacillus cereus, Salmonella typhi, Pseudomonas aeruginosa and Staphylococcus aureus were determined. According to the results, E. coli was more resistant to cinnamon. Also, the nanoemulsion exhibited high inhibitory effects than the pure essential oil. The antibacterial activity of free and nanoemulsified cinnamon oil against E. coli, E. faecium was evaluated by measuring nucleic acid, protein and potassium leakage from the cells. Investigation of the kinetics of microbial deactivation showed that after 24 h incubation, recovery was observed for all treatment and recovery rate of nanoemulsion treatment was slower than that of free cinnamon oil treatment.